1. Field of the Invention
This invention relates to a flocculation basin in a water treatment process of clean water or sewage. More particularly, in a water treatment process for flocculating turbid small particles in water introduced into the basin to floating matters called "flocs", the present invention relates to a flocculation basin which accurately monitors the growth of the flocs and grows them stably and satisfactorily.
2. Description of the Prior Art
In a water treatment process, turbid fine particles are removed after coarse contents are removed. The fine particles make water turbid. Among the turbid fine particles, those which have large particle diameters can be removed by precipitation, but those having particle diameters of several microns can not be removed by precipitation. Therefore, a flocculant or coagulant is added to water in order to flocculate the fine particles to the mass of particles called "flocs", and the resulting flocs are thereafter removed by precipitation.
In the water treatment process of the kind described above, whether or not the flocs are formed satisfactorily affects directly the precipitation and filtration processes as subsequent treatment processes. If the flocculation is not good, the precipitativity of flocs in a settling basin drops. The drop of precipitativity in turn invites the overload of a filtering basin. If the detection of the overload is too late, a critical problem will develop in that the fine flocs flow out from the filtering basin.